An Analysis of Childhood Asthma and Environmental Exposures in Utah

Michelle Gillette, M.P.H.Office of Epidemiology

Utah Department of Health

Asthma in the United States

• Increasing prevalence in all age, sex, and racial groups (NHLBI Data Fact Sheet, 1999)

Trends in Asthma Prevalence by Age

0

10

20

30

40

50

60

70

80

1980 1981-83 1984-86 1987-89 1990-92 1993-94

Year

Rat

e pe

r 1,

000

pers

ons

0-45-1415-3435-6465+

National Heart, Lung and Blood Institute, 1999

Age

Asthma in Utah

• Hospitalization due to asthma– 12.3 asthma cases per 10,000

children ages 0-14 for 1992-1995 (LeFevre, 1997)

• Childhood asthma hospitalization rates at the zip code level – Analysis conducted in four

Urban counties

Previous Study Data:

84 0 4 4 84 1 0 4

84 1 1 6 84 1 0 3

84 1 1 984 1 2 0

84 1 1 8

84 0 8 4

84 0 8 8

84 0 0 684 0 9 5

84 0 6 584 0 2 0

84 0 9 2

84 1 1 784 1 0 6 84 1 0 9

84 1 2 4

84 1 2 184 0 4 7

84

07

0

84

09

4

84

12

3

84

10

78

41

15

84

101

841

11

84 0 9 3

84 1 0 5 84 1 0 8

11 211 310 2

84 1 1 7

84 0 5 4 84 0 1 0

84 0 8 7

84 0 1 4

84 0 2 5

84 0 3 7

84 0 4 0

84 0 4 1

84 0 7 5

84 0 4 384 0 0 3

D A V IS C O U N T Y

M O R G A NC O U N T Y

T h eG r e a tS a lt L a k e

S A L TL A K EC O U N T Y

L a k e s

A s t h m a H o s p i t a l R a t e s ( 1 9 9 2 - 1 9 9 5 )

S ig n i f ic a n t ly L o w e rN o t S ig n i f ic a n t l y D i f f e r e n tS ig n i f ic a n t ly H ig h e r

N o C a s e s R e p o rt e d

F r e e w a y s

C o u n t y B o u n d a r ie sSignificantly Lower

Not Significantly DifferentSignificantly HigherFreeways

Asthma Incidence Rates by Zip Code (1992-1995) Ages 0-14

Salt Lake County

The GreatSaltLake

N

E

S

W

Asthma in Utah

Increased Rate Of Childhood

Asthma

Many Industrial

Emission Sites

Relationship?

In Western Salt Lake County:

Study Objectives

• Analyze the spatial and temporal variation of childhood asthma within four urban Utah counties

• Determine if there is a relationship between childhood asthma development and proximity to industrial emission sources

Study Population

• Study Location– Four urban

Utah counties – Approx. 77%

Utah’s population

• Asthma Cases–ICD-9 code 493–1990-1999–Ages 0-14

Salt Lake City

Salt Lake County

Utah County

Davis County

Weber County

Salt Lake City

GreatSalt Lake

UtahLake

Counties Major Roads Major Lakes

Childhood Asthma Study Area

Data Collection: Asthma Cases

Hospital Discharge Data:•11,522 Cases•Name•Birth Date•Sex•Date of Admit/Discharge•Address at time of hospitalization

Data Collection: Asthma Cases

Birth Certificate Data:•8,932 Unique individuals•Race•Tobacco Use (Mother)•Alcohol Use (Mother)•Congenital Anomalies•Birth Address

Data Collection: Emission Sites

• NPL• CERCLIS• RCRA• TRI• Point Source Emissions

Sources of Hazardous Emissions:

UtahLake

Great Salt

Lake

Industrial Emission Sites (1990-1999)

NPLTRI

CERCLISPSE

RCRA

X

Data Collection: Confounders

• Socioeconomic Data– 1990 and 2000 Census Data

• Access to Healthcare– Proximity to hospital

• Climatological Data– Wind speed & direction, temp,

humidity

Data Analysis: Statistical Tests

• Cluster Identification through Spatial and Temporal Analysis– Are cases close together in space and time?

• Statistical Tests Used – Knox Test– Moran’s I– Gedis-Ord G– Geary’s C

Data Analysis: Statistical Tests cont.

• Relationship between emission sources and asthma cases– Lawson test

• Point-specific analysis– Rule out potential confounding

factors (i.e. socioeconomic & climatological data)

Status of Study

• At this point:– 11,522 cases mapped based on

address at time of hospitalization

– 8,032 cases mapped based on birth address

– 6,094 industrial emission sites identified and mapped

Conclusions

• Previous study indicates increased incidence of asthma in certain areas

• Ongoing analysis to identify clusters and evaluate relationship to emission sources

• Final Results available Fall 2002

Questions?

• Contact Information:Michelle Gillette, M.P.H.Office of EpidemiologyUtah Department of Health(801) 538-6191mgillett@doh.state.ut.us

Funding for this study provided by:

The Agency for Toxic Substances and Disease Registry Cooperative Agreement #U50/ATU887580-03

Additional assistance provided by Dr. R. Wayne Ball, Greg Williams, Amy Coombs, Samuel LeFevre, and the University of Utah Digit Lab

References

National Heart, Lung, and Blood Institute, National Institutes of Health, Centers for Disease Control and Prevention. (1999). NHLBI Data Fact Sheet: Asthma Statistics, January 1999. http://www.nhlbi.nih.gov/health/prof/lung/asthma/asthstat.htm

LeFevre, S., and Ball, R.W. (1997). Health Assessment: Asthma Hospitalization Rates Among Children in Utah.